1. Field of the Invention
The present invention relates to a semiconductor apparatus having a coil.
2. Description of the Related Art
Recently, small-size electronic devices are widely spread, which are a cellular phone, a portable audio device, a PDA, a digital camera, etc. These electronic devices are demanded to be smaller, to have more functions, to have higher performance, etc. As a result, if an electronic device is manufactured, packaging technology, etc. are required for enabling higher density (see, e.g., Japanese Patent Application Laid-Open Publication No. 2002-93847).
In order to complying with such a requirement, recently, for example, an AM/FM tuner is constituted by one (1) package (semiconductor apparatus) and is provided as a commercial product which can be mounted on a portable electronic device. Although a package exists conventionally which stores almost all parts of a tuner as one (1) IC chip (semiconductor chip), for example, an inductor (coil), a varactor diode, etc. of a local oscillator circuit still must be mounted on a printed wiring substrate of an electronic device as an external part along with the package. In the package described here, an IC chip is electrically connected to a conductive path formed on the one side of a resin substrate and is then sealed with mold resin (insulating resin). On the contrary, recently, in order to store external parts into one (1) package, a pattern for a coil is formed on the other side (i.e., the under side of the package) of the substrate of the package, or a capacitor bank is incorporated into an IC chip, instead of a varactor diode which has relatively large dimensions. The capacitor bank is constituted by connecting a plurality of capacitors having capacities differentiated by a predetermined size in parallel and the frequency is changed by sequentially switching the capacities with the use of software. In this way, by using the recent so-called “one-chip” package, a portable electronic device can also be equipped with a function of a radio easily.
By the way, in general, in order to maintain a good frequency characteristic of a LC circuit of the above-described local oscillator circuit, etc., the inductance characteristic of the coil must be set to a predetermined value which maximize, for example, a Q value of the LC circuit to maintain the predetermined value at the time of operation of an electronic device, etc. to which a package is mounted. The inductance described here means the inductance of the coil provided along with the IC chip, etc. in the package mounted on a printed wiring substrate, for example.
However, due to mutual inductance coupling with circuit elements, etc. around the coil, the inductance of the coil may shift from a predetermined value set by, for example, the manufacturer of the package for single package at the time of shipping. With interference of inductive noise from circuit elements, etc. around the coil at the time of operation of the electronic device, etc., the inductance may shift from the predetermined value at the time of shipping.